1. Field of the Invention
The present invention relates to an optical information recording/reproducing apparatus for recording/reproducing information on/from an information recording medium such as an optical card. The term "recording/reproducing apparatus" means a recording apparatus for recording information on an information recording medium, a reproducing apparatus for reproducing information recorded on an information recording medium, and a recording/reproducing apparatus for recording and reproducing information.
2. Description of the Related Art
An optical card has a memory capacity several thousand times to ten thousand times greater than that of a magnetic card. Unlike the magnetic card, the optical card is not rewritable; however, since the optical card has a memory capacity of 1 to 2 Mbytes, it will be widely applied to bankbooks, portable maps, and prepaid cards.
There is a demand for a portable, cost-effective optical information recording/reproducing apparatus for recording/reproducing information on/from an optical card.
Roller movement type optical information recording/reproducing apparatuses are disclosed, for example, in Published Unexamined Japanese Patent Application (PUJPA) No. 63-66770 and PUJPA No. 1-172018. In these apparatuses, an inserted optical card is moved directly by means of driving rollers. An optical head is moved relative to the optical card for information recording/reproducing.
During information recording/reproducing, the speed of the optical card is detected. A clock pattern for generating clock signals is formed on the optical card along the information tracks. Thus, the speed is detected by the clock signals. Based on the detected speed, the speed of the optical card is optimized.
On the other hand, PUJPA No. 62-97174 discloses an apparatus for stably moving an optical card at a fixed speed, without detecting the speed of the optical card.
In this apparatus, a pair of rollers (i.e. a driving roller and a driven roller) are arranged below an optical head. An optical card is clamped between these rollers and moved reciprocally. There are provided other rollers outside the range of reciprocal movement of the optical card. Since the optical card is moved only by the paired rollers, it can stably be moved at a fixed speed.
There is also known an apparatus wherein a shuttle on which an optical card is placed is moved, and the card is not moved by means of rollers. A clock pattern is not formed on the optical card used in this apparatus, and the speed of the card is detected by using a motor having an encoder.
In the apparatuses disclosed in PUJPA No. 63-66770 and PUJPA No. 1-172018, however, a data area for a user on the optical card is reduced since the clock pattern is formed on the card.
In addition, an optical card without a clock pattern cannot be used in this apparatus. That is, the optical card for the apparatus detecting its speed without a clock pattern cannot be used. Thus, compatibility between the apparatuses using and not using the shuttle is lost.
In the apparatus wherein the optical card is moved by only the rollers, a single rotation of the roller does not coincide with a single rotation of the motor. This is due to backlash of gears in a transmission mechanism provided between the motor (i.e. driving source) and the driving roller, or slack in a belt. Thus, in order to move the optical card at an exact speed, the speed of the card must be detected. Unless the speed of the card is detected, exact information recording/reproducing cannot be performed on the optical card.